Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real context beyond that: results are scoped to the key's permissions, the call is cursor-paginated, and the read scope is required. It does not state the default/exact return shape, but no output schema exists to cover that either.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short, front-loaded sentences: what it returns, the underlying endpoint, then pagination and auth. No filler, and the scoping constraint comes first where it matters most.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple, zero-required-parameter list tool with no output schema, the description covers scope, endpoint mapping, pagination, and auth requirement — enough to invoke correctly. Missing only an explicit statement of the default page size behavior, which the schema already carries.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so limit and cursor are already documented in the schema. The description adds only the 'cursor-paginated' framing, which reinforces rather than extends the cursor parameter — baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('List the channels') plus the scoping constraint that only channels the calling key can see are returned. It does not explicitly distinguish itself from the sibling list_sources, so the agent must infer the channel/source split from the resource noun alone.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives a prerequisite ('Requires the key's read scope') which is genuine usage guidance, but never says when to prefer this over list_sources or query_channel. Usage is implied by resource name rather than stated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.